Reclamation baghouse dust comprises material originating from particulates emitted during melting of aluminum scrap metal. Generally, the dust material is collected and retained on filter bags employed in dust collector systems. Reclamation baghouse dust generally comprises carbonaceous material containing up to about 50% carbon. Thus, baghouse dust exhibits a tendency to undergo spontaneous combustion. The dust material also contains a significant concentration of heavy metals, the specific amounts and types of heavy metals being dependent on the raw material being processed. In many instances, the concentration of heavy metals contained in the dust material exceeds limits imposed by the Environmental Protection Agency, whereby the dust material is classified as hazardous.
Several method are presently practiced for rendering reclamation baghouse dust nonhazardous. These methods are generally known as stabilization and solidification. According to the stabilization method, the baghouse dust is mixed with an alkaline material such as lime or cement. A chemical reaction occurs in the mixture which limits the solubility of toxic components and/or converts the toxic components to a non-toxic form. According to the solidification method, the baghouse dust is compressed into a block or bricks of high structural integrity. However, each of these methods has a significant disadvantage. For example, in the stabilization method, the resulting product still exhibits a significant tendency to spontaneously combust. In the solidification, heavy metals contained in the compressed product are easily leached therefrom. Accordingly, a need exists for an improved treatment method for reclamation baghouse dust which overcomes the disadvantages of the presently employed methods.
The Duyvesteyn U.S. Pat. No. 4,605,435 disclose a method for converting iron-containing steel plant dust into recyclable agglomerates. The method comprises mixing the dust with water and cement and pelletizing the resulting mixture. The Allen U.S. Pat. No. 3,870,507 discloses an additional method for making briquettes from solid particulate steel mill wastes such as blast furnace flue dust, basic oxygen furnace dust and the like. The wastes are mixed with a hydrocarbonaceous binder and the resulting mixture is formed into briquettes. The Pietsch et al U.S. Pat. No. 4,105,457 discloses a similar method for forming briquettes consisting of agglomerated metallized particles or mineral ore particles and a binder consisting of hydrated lime, sodium silicate and water. The Ravitz U.S. Pat. No. 3,864,092 discloses a method for preparing metal scrap materials in a block formed together with a selected bonding material such as cement. The Behr U.S. Pat. No. 3,107,166 discloses additional methods wherein metal scrap materials are compressed into briquettes and provided with a plastic or other non-metallic coating. The Gnaedinger U.S. Pat. No. 4,496,267 discloses a method for using incinerator ash in a pavement composition wherein the incinerator ash is reacted with lime for several days. Finally, the Osborn et al U.S. Pat. No. 2,206,117 discloses a method for recovering metal values from fume deposits wherein the deposits are compressed at temperatures at which the desired metals for recovery are molten.
However, none of these references disclose a treatment method for reclamation baghouse dust which overcomes the disadvantages noted above and provides a nonhazardous product.